1. Field
The following description relates to a matrix switching type touch panel, and more specifically, to a matrix switching type touch panel capable of preventing the boundaries between areas where a transparent electrode exists and areas where a transparent electrode does not exist from becoming visually distinguishable, while preventing the transparent electrodes of the touch panel from causing the Moire effect.
2. Description of Related Art
In general, a matrix switching type touch panel comprises a plurality of touch pads disposed in a visible area on a substrate in a dot matrix format, the touch pads spaced from one another; and a plurality of signal lines disposed in the space between the touch pads, each signal line connecting a touch pad and a touch driving circuit of a invisible area.
As illustrated in FIG. 1, in a conventional matrix switching type touch panel, transparent electrodes are patterned on a substrate 10, forming touch pads 20 and signal lines 30, and thus a visible area A1 may be divided into an area where transparent electrodes exist and the remaining area where transparent electrodes do not exist. Herein, due to difference of penetration ratio, reflectance, and color etc. between an area where transparent electrodes exist and an area where transparent electrodes do not exist, there is a problem of a patterning mark occurring, that is the area where transparent electrodes exist becoming visible.
In such touch screen panels, a coating layer is provided in order to resolve the visual difference between the area where transparent electrodes exist and the area where transparent electrodes do not exist. However, adding a coating layer increases the cost and complicates process, and further, even if a coating layer is added, in a matrix switching type touch panel, numerous signal lines 30 are disposed in a straight line format in a visible area A1 on a substrate 10, and thus may become easily visible.
Furthermore, in the signal lines 30 that connect touch pads 20 and a touch driving circuit 40, if the distance between the touch driving circuit 30 and the touch pads 20 are far apart, the resistance and parasitic capacitance increase as the wire length of the signal lines 30 gets longer. Therefore, the signal lines 30 are designed to have greater width as the wire length gets longer as in FIG. 2. However, this may cause a structural problem since the boundaries between the signal lines 30 in some areas are disposed densely thereby increasing the visibility.
Furthermore, if the line of the signal electrode of the touch pad corresponds to the line of the pixel electrode of the liquid crystal panel, the pattern of two parallel lines spaced by a certain distance will overlap each other as in FIG. 3, thereby causing an optical defect. That is, the screen quality will be deteriorated by the Moire effect of displaying a line pattern having a predetermined distance D.